CHAPTEE II. 



INORGANIC PROXIMATE PRINCIPLES. 



THE inorganic substances are present in the animal body in great 

 variety. Some of them, such as water arid the salts of lime, constitute 

 also a large proportion of the mass of the tissues and fluids in which 

 they are found ; others present themselves in comparatively small 

 quantity. Some of them are found universally in all regions of the 

 body, while others are met with only in particular tissues or fluids ; but 

 there are hardly any which do not appear at the same time as con- 

 stituents of several different parts. As their name indicates, these 

 substances are met with extensively in the inorganic world, and form a 

 large part of the crust of the earth. Notwithstanding, however, their 

 inorganic nature, they are also essential constituents of the animal 

 frame. They are accordingly necessary ingredients of the food and 

 drink, and no regimen would be capable of supporting life indefinitely 

 which did not contain these materials in due proportion. 



The group of inorganic proximate principles includes the following 

 substances : 



Water ; Potassium phosphate ; 



Sodium chloride ; Potassium sulphate ; 



Sodium phosphate ; Potassium carbonate ; 



Sodium biphosphate ; Lime phosphate ; 



Sodium sulphate ; Lime carbonate ; 



Sodium carbonate ; Magnesium phosphate ; 



Potassium chloride ; Magnesium carbonate. 



Beside the above-named proximate principles there are found, as 

 constant ingredients of the incombustible residue of various parts of 

 the human body, iron, silica, and fluorine ; but it is not certainly known 

 in what form of combination these substances originally existed in the 

 animal solids and fluids. Sometimes, but not always, there are indica- 

 tions of the presence, in minute quantity, of copper, manganese, and 

 lead, also in some unknown forms of combination. 



The most important of the inorganic proximate principles, considered 

 in regard to their quantity or the part which they play in the vital 

 actions, are the following : 



1. Water, H 2 0. 



Water is universally present in all the tissues and fluids of the body. 

 It is abundant in the blood and secretions, where its presence is indis- 

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